The primary objective of this project is to investigate in vitro, the regulation of granulosa cell FSH receptor content and the functional responsiveness of the receptor in the porcine ovary. Cellular FSH receptor levels will be determined by the specific binding of 125 I-FSH and receptor responsiveness via the ability of whole cells and/or cell membranes to generate cAMP in response to FSH. Radioautography will be used as a tool to monitor the cellular distribution of FSH receptor. Specifically, studies will focus on: (a) the pattern of granulosa cell FSH receptor content and FSH responsiveness as a function of follicle development using cells isolated from follicles of differing size from the ovaries of prepubertal and adult cycling animals. (b) endocrine and non-endocrine factors necessary to maintain and/or modulate FSH receptro and responsiveness during moderate-term monolayer culture. (c) differences between FSH receptro content and responsiveness in granulosa cells isolated from atretic and non-atretic follicles and how these cells differ in their response to endocrine stimuli during culture. (d) characteristics of FSH/receptor binding, internalization and degradation in vitro. These studies will provide direct, basic information regarding the regulation of a receptor that is crucial for normal follicle development. The knowledge gained through thest studies using a large domestic animal may provide a basis with which to study FSH receptor regulation in cells from human ovaries.